The proposed research is designed to investigate certain of the biochemical and physiological processes that are fundamental to the maintenance of a normally functional cornea. In order that the tissue be transparent a constant level of hydration must be maintained in the stroma and this necessitates the continuous extrusion of water. The molecular mechanisms responsible for this energy-requiring process are known to reside in the endothelium and are presumed to involve active transport of one or more ions. The hypothesis that bicarbonate transport is the driving force for water movement will be examined by measuring bidirectional fluxes of this ion across the endothelium and by observing the effects on stromal hydration of changes in bicarbonate or CO2 centrations and in the activity of carbonic anhydrase. The activity and distribution within the endothelium of the Na-K-stimulated and bicarbonate-stimulated ATPases will also be measured in order to assess their postulated roles in the coupling of energy sources to ion transport. Since the integrity of membrane components, especially lipids, is critical for the maintenance of both normal permeability characteristics of the cells and normal activity of lipoprotein enzyme complexes, it is possible that the failure of the fluid transport mechanism in vitro is brought about by degeneration of these components. The mechanism of the protective effect of glutathione and other anti-oxidants will be studied to determine whether their function is to protect against peroxidation of lipids by maintenance of a non-oxidative environment, and whether failure in vitro results from deficiencies in metabolites essential for renewal of membrane structure. The role of the bicarbonate ion in retinal function will also be studied, again through investigation of the activity and distribution of the bicarbonate-stimulated ATPase. Its effect on ADP levels at different sites in the retina is postulated to account for the increased metabolic activity and electrophysiological response to light which are caused by bicarbonate.